This invention relates generally to the field of magnetic recording and reproduction, and more specifically to a wiring arrangement for driving a pancake-wound spiral conductor of a thin film magnetic read/write head.
In general, the use of thin film magnetic elements is well known in the magnetic recording art. Such a thin film magnetic read/write head is shown in FIGS. 1 and 2 (prior art), corresponding to FIGS. 1 and 2 of U.S. patent application Ser. No. 313,841, assigned to the same assignee as the present application. The thin film recording head 10 comprises a bottom conductor layer 20 formed on a substrate 30, with a first insulator layer 60a deposited on the first conductor layer 20. Windings 40 are disposed on top of the first insulator layer 60a, and a second insulator layer 60b is disposed on top of windings 40 A pole piece 50 is then provided to the upper surface of the second insulator layer 60b such that one end 56 of pole piece 50 is separated from conductor layer 20 by the first insulator layer 60a to form an air gap 52. The pole piece 50 extends over one side of the windings 40 such that the second end 54 of the pole piece 50 directly contacts the bottom conductor layer 20 at the axial center of the windings 40. An overpass conductor 46 connects the inner end of the windings 40 to a first connecting pad 42. A second conductor 48 connects the outer end of the windings 40 to a second connecting pad 42'. The connecting pads 42, 42' are in turn connected to current drivers 44, 44', respectively. In operation, current from the current drivers flows through the windings 40 to produce a magnetic field at the above-mentioned gap 52. The produced magnetic field serves to record magnetic spots on a magnetic tape or other such recording medium 70. In a reverse manner the read/write head operates to read magnetic data previously recorded on recording medium 20.
The formation of the thin film head of FIGS. 1 and 2 may be described in more detail as follows: A silicon or ceramic substrate 30 is coated with a first conductor layer 20 which consists of a permalloy [NiFe] magnetic material. A first insulating layer 60a of silicon dioxide is then formed on the permalloy layer 20. Next, aluminum (or other conductors such as Au, Ag, or Cu) is deposited and patterned into windings 40. The windings 40 are covered by a second silicon dioxide insulating layer 60b. The overpass conductor 46 typically comprises either the same materials as the windings 40 or permalloy, as discussed in IBM Disk Storage Technology, February 1980, page 7. Although the overpass conductor in FIG. 2 is disposed beneath the second insulating layer 60, in some prior art thin film devices the overpass conductor is provided on the upper surface of the second insulating layer 60. In addition, a second pattern winding may be provided. For example, IBM produces a recording head using two layers of windings with four turns per layer, and "DASTEK" makes an improved recording head having five turns in one layer and four turns in another layer. Although the present invention will be described with reference to one layer of windings, it is to be understood that the invention is not to be limited thereto. After formation of the windings 40, the pole piece 50 is formed of permalloy and is situated so that one of its ends 54 contacts the bottom permalloy layer 20 and its other end 56 is separated from the bottom permalloy by the first insulating layer 60a in order to provide a recording gap 52.
With the overall trend towards miniaturization, a need has developed for the above-described thin film magnetic read/write head to be reduced in size. One method of reducing the size of a thin film device is to eliminate one or more of the layers coated on the substrate. However, in the prior art, no one has developed a structure or method by which the layers of thin film magnetic read/write head could be removed or eliminated without rendering the device inoperative for its intended purpose.